Update README.md

Add a message and link to CONTRIBUTING.md in the README.md file.
Minor formatting adjustments
Add a link to the license file in the readme
Update CONTRIBUTING.md
Rename license.txt to LICENSE.md
Update LICENSE.md text to the standard Apache 2 declaration
Update link to LICENSE file in the README
Update CONTRIBUTING.md

Updated CONTRIBUTING.md to specify that the `this` keyword should be avoided.
Fixes #35: Solution file should be located in the root of the repository
Update README.md
Update README.md
Update README.md
Update README.md

Add links to Google Groups and JabbR
Update README.md

Add a link to the samples repository
Remove samples directory
Merge branch 'master' of github.com:scriptcs/scriptcs

* 'master' of github.com:scriptcs/scriptcs:
  Update README.md